Fuel injection apparatus



March 26,1946. L40. FRENCH ,39

1 FUEL INJECTION APPARATUS Filed May '27, 1944 MENTOR. Qua, o. 'IMJQ Patented Mar. 26, 1946 UNITED STATES PATENT OFFICE FUEL INJECTION APPARATUS Louis 0. French, Milwaukee; Wis.

Application May 27, 1944, Serial No. 537,569

Claims. (01. 103- 11)- The invention relates to fuel injection apparatus. for internal combustion engines.

The unit type of fuel injector practically eliminates the disadvantages occasioned by pressure waves in fuel lines but as present constructed depends upon the injection plunger to time and meter the fuel charge. As a result the plunger must have a very close fit in its barrel and a small. amount of wear seriously effects its pressure producing ability and metering efliciency. Also the plungers return is dependent upon its mechanical actuator and usually upon engine speed. A proposal has been made to provide a unit fuel injector in which the fuel injection plunger is given a variable stroke by compression of a metered body of liquid under relatively low pressure and of larger volume than the fuel charge between an engine controlled piston and an hydraulically operated piston, but in. this proposal the hydraulically operated piston was a relatively long and heavy member, unsuited for high speed operation, and not positively limited in its movement to filling position and special mechanism was provided for turning both the hydraulic piston. and the injection plunger in addition to the engine. controlled piston to vary the amount and time of injection and no adequate means was provided for filling the space between the engine controlled piston and the hydraulic piston or for permitting the return of the hydraulic piston and the injection plunger in advance of and independent of the return of the engine controlled piston. The above discussed proposal will be found in United States Letters Patent No. 1,864,860, dated June 28, 1932, to Carl D. Salisbury. One object of this invention is to provide a unit injector of the hydraulic variable stroke type in which the hydraulically operated piston is a simple low inertia member positively limited in its movement to pump filling position and together with the injection plunger free to be returned to said filling position immediately after release of pressure between said hydraulically operated piston and the engine controlled piston so that quick cut off of the fuel spray and efficient charging of the high pressure injection pump is assured. Furtherv more, the structure has been simplified by using the engine operated piston as the member for determining the time of the beginning of and termination of the injection period. While there are two additional pistons as compared to the direct mechanically operated injector, these pistons are relatively large and correspondingly easier to machine and finish and have a much longer useful life and the injection plunger itself has a greater sealing. area in its barrel and may be just aplai'n round rod. Furthermore, the diameters of the injection plunger may be smaller than it is practically possible to use in the directly operated piston controlled by-pass type of pumps and injectors.

A further object of the invention is to provide an injection device in Wh'ichthe engine controlled piston and the hydraulically operated piston are of the same diameter and work in the same barrel.

A further object of the invention is to provide a fuel injection device or pump in which means are provided to utilize the pressure of the released power transmitting. fluid to check the movement of the hydraulically operated piston and start or assist it on its. return stroke.

The invention further consists in the several features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawing:

Fig. 1 is a vertical sectional view through an apparatus embodying the invention;

Fig. 2 is a detailed horizontal sectional view taken. on the line 1-2 of Fig. 1.

Fig. 3 is a detailed horizontalsectional view taken. on the line 3-3 of Fig. 1 with certain modifications;

Fig. 4 is a detailed vertical sectional view taken on the line 1-4- of Fig.2

Figure 5 is a detailed vertical sectional View showing certain modifications.

Referring to the drawing, the numeral 5 designates a casing, 6 the fuel injection or pump plunger, 1 the barrel for said plunger, 8 an hydraulically actuated piston, 9 an engine operated or controlled piston, ill a barrel for the pistons 8 and 9, I' l aspring for returning the plunger 6 and piston 8, l2 a spring; for returning the piston 9, IS a stop on the piston 8, M a discharge valve, l5 a spring to close said valve, [6 a nozzle memher, and We. clamping nut.

The casing 5 is provided with alined. bores l8 and. I9; and its lower end 20 of reduced: diameter is threaded to take theelamping nut I1. The barrel 1 fits in the bore l8, and its flanged head and. the part I 6 are held in assembled relation with said casing by the clampingsleeve nut ll vghich engagesthe threaded end 21 of the casmg The barrel l0 fits the bore l9 and is held at itsupper end in engagement with the casin by screws 2-| passing through its flanged upper end 22- and anchored to said casing, a sealing. gasket 23 being interposed between said flange 22 and the top of the casing. The barrel terminates above the bottom of the bore 20 to form a chamber 24.

The piston 8 reciprocates in the lower end ,of the barre1 9 and the stop l3 formed by a flange on said piston engages with the lower end of the barrel E9 in the upper position of said piston, the head of the plunger 6 having non-centering contact with the piston 8 and moved thereagainst by the spring I l. The piston 8 is quite short and light so that its inertia is low and does not interfere with its high speed operation.

The piston 9 reciprocates in the barrel l and has a timing control edge 25 at its inner end and a Volume control edge 26 spaced therefrom, these edges cooperating with an inlet port 27 and a relief port 28, respectively, formed in the barrel Ill-,

the edge 26 forming one side of an annular recess 29 formed in said piston and connecting with the actuating fluid pressure chamber 30 by a longitudinal bore 3| and a communicating transverse bore 32. These control edges with the spaced ports are not claimed as new per se, but their association with a piston such as the piston 9 is new and they cooperate with other parts to prevent overtravel of the piston 8 and insure its prompt return. The piston 9 preferably has a leakage groove 33 adapted to register with a port 34 in the upper part of the barrel in the upper position of said piston. This port 34 may connect by an extension of groove 4| with the outlet passage 35 or with the return pipe (not shown) connected with said outlet.

The inlet port 21 is supplied with operating fluid from any suitable low pressure supply through a supply pipe 36 connected with a threaded passage 31 in the casing 5 and preferably having a spring closed check valve 38 mounted therein. The passage 37 connects by a grooved passage 39 in the barrel ID with the port 21.

The relief port 28 is connected by a relatively large passage 4!], formed by a groove in the barrel, with the chamber 24 which connects by a separate passage 4| formed by another groove in the barrel H! with the outlet 35 which may be connected by suitable piping (not shown) to the supply tank. The passage 4| or a part thereof is'of reduced diameter forming a throttling restriction to prevent too rapid dissipation of pressure'in the chamber '24 on the release of pressure fluid from the chamber 30 when the piston 9 uncovers the relief port 28, so that operating fluid released under pressure from the chamber 30 flows into the chamber 24 and through the throttling effect of said restriction expends the greater part of its pressure energy in said chamber before flowing to the outlet and thus exerts this energy against the piston 8 to assist in its quick return.

The high pressure fuel pump may be supplied with fuel by a separate pipe suitably connected with an annular groove 43 in the barrel 8 and connected with its interior by the diametrically disposed inlet ports 44 controlled by the piston 6, or where the fuel is used as the actuating fluid, the sides of the barrel are provided with flats 45 providing passages connecting the groove 43 with the chamber 24. In those instances where a volatile hydrocarbon or alcohol is used as fuel, the fuel supply is preferably separate from the supply of actuating fluid, preferably then a lubricant, to, the chamber 30 which lubricant is important in lubricating the plunger 6 when fuels like gasoline or alcohol are used.

way of port 4| out of the outlet 35.

downward movement of the piston 8 and plunger 6 in opposition to the spring I I, thus mowing said plunger past the ports 44 and putting the fuel in the chamber 4'! under pressure until that high pressure is reached which causes the fuel to overcome the action of the spring l5 and open the valve 14 and allow fuel to pass through the spray nozzle l6 into the combustion chamber of the engine. During this movement any low pressure fluid in the chamber 24 may pass by The continued downward movement of the piston 9 brings its control edge 26 into registry with the port 28, and under all conditions except, where desired, that of full load, hydraulic fluid is then bypassed from the chamber 30 through bores 3| and 32 and recess 29, port 28, and conduit 40 to the chamber 24 beneath the piston 8, thus quickly reducing the pressure in the chamber 30 and causing the valve 38 to close and temporarily causing an increase of pressure in the chamber 24 which together with the force exerted by the spring ll causes a quick return of the piston 8 and the plunger 6 to their initial position, determined by the stop 13 independently of and before the piston 9, thus causing a quick closing of the discharge valve M to prevent dribble at the nozzle and increasing the time available for the refilling of the chamber 41 with a new charge of fuel. The control edges 25 and 26 are spirally inclined so that by angularly shifting the position of the piston 9, the time of beginning and ending of the pressure fluid cycle and hence the high pressure fuel cycle may be varied. For this purpose the piston 9 has a cap member 48 clamped thereto by a nut 49, and this cap has a series of projections or teeth 50 formed thereon or secured thereto which mesh during the reciprocatory movement of said piston'with a splined sleeve 5| rotatably mounted on the upper portion of the casing 5 and retained in operating position by a flange 52 on the barrel l0 and a shoulder 5' on said casing and provided with an arm 53 for manual or governor operation.

After completing its downward. or inward stroke, the piston 9 is returned by the spring [2, and when it passes the port 21, the chamber 30, and the recess 29 are quickly filled with operating fluid due to the vacuous condition of these spaces. Inclination of the control edges 25 and 26 is such that in one position of the piston 9 the port 28 is uncovered as the port 2'. is closed, so that no operating fluid will be compressed between the .pistons 8 and 9 on. the working stroke of said piston 9. For full load conditions after the port 21 is closed by the piston 9 both pistons 9 and 8 with the operating fluid between them may move together during the full stroke of the piston 9.

It will be noted that the check valve 38 prevents the fluid at its release pressure from escaping into the supply. pipe 35.

Instead of using spaced inlet and relief ports the barrel l 9 may be provided with oppositely dispos'ed vports 54 and 55, both' of which may act as inlet ports and one of which, for example, the

port 55 cooperates with control edges 56' and 51 on thepiston'58 to control the duration of injection, the edge forming a side of an annular recess 59 in said piston. For no delivery the edges 5t and 51 are connected at one point by slot til alineable with the port 55 on a rotation of the plunger as in the first described construction. In this construction the port 55 at the beginning of injection acts as an inlet port but subsequently when the control edge 5! comes into registry with it acts as a relief port so that the fluid suddenly released through the port 55 is conducted by the passage 6| into the chamber 24 to assist in the return of the piston 8. With this construction angular shifting of the piston 58 relative to the ports 54 and 55 varies the time of ending of the movement of the piston 8 and hence the injection or pump plunger 6. The particular form of the control edges for the piston 58 and the spaced ports are not new per se, but their association with a piston, such as the piston 53 as above described, is new and prevents outtravel of the piston B and insures its prompt return. A separate fuel supply passage 62 in the casing 5 connects with an annular groove 63 formed in the barrel 1 which at its lower end communicates with oppositely disposed inlet ports 64 in said barrel controlled by the plunger 6.

With the above arrangement the pressure of the actuating fluid may be relatively low, for example between fifty to five hundred pounds per square inch and the pressure of the injected fuel may be at fifteen hundred to four or flve thousand pounds per square inch by the proper selection of ratios of diameters for the piston 3 and the plunger 6. The outlet opening 35, as usual, c0nnects with the reservoir or the suction side of the pump supplying the operating fluid to the device.

While the invention has been more particularly shown and described as a unit injector, it may be used as a pump associated with an engine having fuel lines leading from the pump to the spray devices in the heads of the engine.

I desire it to be understood that this invention is not to be limited to any particular form or arrangement of parts except in so far as such limitations are included in the claims.

What I claim as my invention is:

1. In a fuel injection apparatus, variable stroke mechanism for a fuel injection pump having a fuel expressing member, the combination of a casing having a cylinder to receive an actuating fluid, an engine controlled piston working in said cylinder, a hydraulically operated piston for direct connection with the fuel expressing member of said pump working in said cylinder, inlet and variable relief means for the actuating, fluid between said pistons controlled by-said engine controlled piston, said relief means being varied by relative rotation between said cylinder and engine controlled piston, stop means to positively limit the return position of said hydraulically operated piston, a chamber in said casing into which said hydraulic piston moves on the expressing stroke of said pump, a passage connecting said chamber with said relief means, and a return passage for the actuating fluid distinct from said inlet means also connected to said chamber, the by-passing of actuating fluid to said chamber permitting it to act on said hydraulically operated piston to assist its return independent of the return of said engine controlled piston.

2. In a fuel injection apparatus, variable stroke mechanismforfa fuel injection pump having a fuel expressing member, the combination of a casing" having a'cylinder to receive an actuating fluid, an engine controlled piston Working in said cyl'in'derja hydraulically operated piston for direct'connection with the fuel expressingmember "of said pump Working in. said cylinder, inlet mean for said cylinder including a control edge on the engine controlled piston for admitting actuating fluid between said pistons, variable actuating fluid release means including a control edge on said engine controlled piston, said relief means being varied by relative rotation between said cylinder and engine controlled piston, and stop means to positively limit the return position of said hydraulically operated piston.

3. In a fuel injection apparatus, variable stroke mechanism for a fuel injection pump having a fuel expressing member, the combination of a casing haying a cylinder to receive an actuating fluid, an engine controlled piston working in said cylinder, a hydraulically operated piston for direct connection with the fuel expressing member of said pump working in said cylinder, inlet and relief means for the actuating fluid between said pistons controlled by said engine controlled piston including an inlet port and a port spaced therefrom controlling the relief of pressure fluid, said engine controlled piston having control edges angularly shiftable relative to said ports and cooperating therewith to determine the time and duration of compressing of the actuating fluid between said pistons, spring means to return said hydraulically operated piston and means for hydraulically connecting together opposite sides of said hydraulically operated piston on the opening of said relief port to permit return thereof by said spring independent of said engine controlled piston.

4. In a fuel injection apparatus, variable stroke mechanism for a fuel injection pump having an expressing member, the combination of a casing having a cylinder to receive an actuating fluid, an engine controlled piston working in said cylinder, a hydraulically operated piston for direct connection with the fuel expressing member of said pump working in saidcylinder, inlet and variable relief means for the actuating fluid between said pistons controlled by said engine controlled piston, said relief means being varied by relative rotation between said cylinder and engine controlled piston, a chamber in said casing into which said hydraulic piston moves on the expressing stroke of said pump, a pass-age connecting said chamber with said relief means and a return passage for the actuating fluid distinct from said inlet means leading from said chamber and having a throttling restriction therein to permit temporary retention of the released actuating fluid in said chamber to utilize the pressure energy therein to assist the return of said hydraulically actuated piston independent of the return of said engine operated piston.

5. In a fuel injection apparatus, variable stroke mechanism for the fuel injection pump having a fuel expressing member, the combination of a casing having a bore forming a chamber, a barrel to receive an actuating fluid mountedin said bore with its inner end forming a wall of said chamber, said barrel having inlet and relief ports for the actuating fluid, a supply passage for said inlet port, an hydraulically operated piston working in said barrel and chamber and provided with a laterally projecting stop part eng-ageable with the inner edge of said barrel to limit its return position, an engine controlled piston working in said barrel and angularly shiftable relative thereto and provided with control edges cooperating with said ports to determine the duration of comthrottling restriction therein to permit temporary retention of the released actuating fluid in said chamber to utilize the pressure energy therein'to assist the return of said hydraulically actuated 5 piston independent of the return of said engine operated piston. v

' LOUIS o. FRENCH, 7 

